Conventional inverter devices that function as driving devices, for example, for driving motors (for example, induction motors), which are the loads, at variable speeds by using a commercial power supply are configured to include a converter rectifier (AC/DC conversion unit) connected to a commercial power supply, a smoothing unit that stores DC power, a charging circuit that includes a charging resistor, a switching element, and a reverse-connected diode, and charges the capacitor (smoothing capacitor) of the smoothing unit, an inverter unit (DC/AC conversion unit) connected to the motor, and the like.
Moreover, conventional inverter devices include positive and negative DC terminals (P, N) so as to operate by receiving power (DC power) from a DC common bus even if power is not supplied from a commercial power supply. Typically, a brake device for preventing overcurrent during regeneration is connected to this DC common bus. Moreover, this brake device is typically provided with a brake resistor that consumes power (regenerative power) during regeneration.